For whom, and why
Accessibility is not for "others": permanent, temporary and situational disabilities, and the accessibility tree a screen reader sees.
Semantic HTML: 80% of the work
A native button does for free what a clickable div never will. Landmarks, heading order, and the find-the-5-problems lab.
Keyboard and visible focus
Tab, Enter, Escape: your whole site must work without a mouse. Visible focus, skip links, and the test everyone forgets.
Alt text
Describe the function, not the picture. When to fill the alt, when to leave it empty, and why "image of" pollutes.
Accessible forms
A clickable label tied to its field, announced errors, never color alone. Repair a broken form, piece by piece.
Contrast and color
4.5:1 for text, 3:1 for large text and UI: the WCAG ratios explained, and information never carried by color alone.
ARIA and real testing
The first rule of ARIA: do not use it. When HTML is not enough, how to test for free (keyboard, axe, NVDA), and the 2026 obligations.
What you will learn
Structure with semantic HTML: native elements do 80% of the accessibility work for free
Make everything keyboard-operable, with visible focus and large enough targets
Write useful alt text, forms with labels and announced errors, passing contrast ratios
Use ARIA as a last resort, and audit for free: keyboard, axe DevTools, screen reader
Prerequisites: the HTML and CSS basics from this site. Labs run in the browser (fix the code, find the problems); the screen reader test is guided for home (free NVDA, built-in VoiceOver). Nothing to buy.